Capacitive pressure sensor
First Claim
Patent Images
1. A pressure sensor in a wheel, the wheel including a rim and a tire, the pressure sensor comprising:
- a first conductive layer;
a second conductive layer, wherein the first and second conductive layers form a first capacitor; and
a compressible dielectric contiguous to the first conductive layer and the second conductive layer;
wherein the compressible dielectric is formed to have delimited structures configured to adjust an average density of the compressible dielectric; and
wherein the capacitor is configured to vary a capacitance in response to pressure changes within the tire.
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Abstract
A capacitive pressure sensor comprises a pair of conductive plates surrounding a compressible dielectric to form a capacitor. Changes in pressure create changes in the capacitance of the capacitor, which in turn may be measured to determine the changes in pressure. The pressure sensor may be constructed to be temperature and centripetal force compensated so that it may be positioned in a tire. A further embodiment uses the conductive plates to form a radiating element for the sensor such that it may wirelessly communicate with a remote interrogator.
37 Citations
40 Claims
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1. A pressure sensor in a wheel, the wheel including a rim and a tire, the pressure sensor comprising:
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a first conductive layer; a second conductive layer, wherein the first and second conductive layers form a first capacitor; and a compressible dielectric contiguous to the first conductive layer and the second conductive layer; wherein the compressible dielectric is formed to have delimited structures configured to adjust an average density of the compressible dielectric; and wherein the capacitor is configured to vary a capacitance in response to pressure changes within the tire. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A pressure sensing system, comprising:
a vehicle, including; a control system; and a wheel, comprising; a rim; a tire surrounding the rim and sealing a gas under pressure within a cavity formed by the tire and the rim; a pressure sensor positioned within the cavity, wherein the pressure sensor is configured to sense pressure within the tire, and wherein the pressure sensor includes; a first conductive layer; a second conductive layer, wherein the first and second conductive layers form a capacitor; a compressible dielectric contiguous to the first conductive layer and the second conductive layer; wherein the compressible dielectric is formed to have delimited structures configured to adjust an average density of the compressible dielectric; and wherein the capacitor has a capacitance that varies according to pressure changes within the cavity; and a remote communication device associated with the pressure sensor, wherein the remote communication device is configured to communicate information from the pressure sensor to a remote location. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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26. A method of sensing pressure of a gas in a cavity, the method comprising:
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measuring capacitance associated with a first capacitor positioned within the cavity, wherein the first capacitor includes a compressible dielectric material and a pair of conductive layers, and wherein changes in capacitance are related to changes in pressure applied to the compressible dielectric material; compensating the measured capacitance for rotational forces, wherein said compensating includes providing a second capacitor associated with the first capacitor, wherein the first capacitor experiences compression during rotational force application and the second capacitor experiences expansion during rotational force application; and communicating information about the changes in pressure to a remote location using at least one of the pair of conductive layers as a radiating element. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34)
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35. A method of sensing pressure in a tire, the method comprising:
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determining tire pressure changes based on changes in a compressible material of a pressure sensor positioned within a cavity between the tire and a rim associated with the tire, wherein the changes in the compressible material affect a capacitance of a capacitor formed from a pair of conductive layers and the compressible material of the pressure sensor, and wherein the capacitor is positioned within the tire parallel to a direction associated with rotational forces to compensate for rotational forces as the tire rotates; and interrogating a remote communication device associated with the pressure sensor to convey information about the tire pressure changes in the cavity, wherein the information about the tire pressure changes in the cavity is conveyed using at least one of the pair of conductive layers as a radiating element. - View Dependent Claims (36, 37, 38)
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39. A method of sensing pressure of a gas in a cavity, the method comprising:
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measuring capacitance associated with a first capacitor positioned within the cavity, wherein the first capacitor includes a compressible dielectric material and a pair of conductive layers, wherein the compressible dielectric material is formed of delimited structures configured to adjust an average density of the compressible dielectric material, and wherein changes in capacitance are related to changes in pressure applied to the compressible dielectric material; and communicating information about the changes in pressure to a remote location using at least one of the pair of conductive layers as a radiating element.
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40. A method of sensing pressure in a tire, the method comprising:
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determining tire pressure changes based on changes in a compressible material of a pressure sensor positioned within a cavity between the tire and a rim associated with the tire, wherein the changes in the compressible material affect a capacitance of a capacitor formed from a pair of conductive layers and the compressible material of the pressure sensor, and wherein the compressible material is formed of delimited structures configured to adjust an average density of the compressible material; and interrogating a remote communication device associated with the pressure sensor to convey information about the tire pressure changes in the cavity, wherein the information about the tire pressure changes in the cavity is conveyed using at least one of the pair of conductive layers as a radiating element.
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Specification